North Korea has warned that planned joint US and South Korean military drills are pushing the peninsula to the brink of war as a US military commander headed to an island devastated this week by a North Korean artillery barrage.

North Korea's state news agency said drills this weekend involving South Korean forces and a US nuclear powered supercarrier in waters south of Tuesday's skirmish between the two countries are a reckless plan by "trigger-happy elements" and target the North.

"The situation on the Korean peninsula is inching closer to the brink of war," the dispatch from the Korean central news agency said.

The comments came ahead of a planned visit today by General Walter Sharp, the US military commander in South Korea, to the island targeted by the North Korean attack to show solidarity with ally Seoul.

Though North Korea regularly threatens to rain munitions down on its rival, the two Koreas are required to abide by an armistice signed in 1953 at the end of their three-year war.

North Korea does not recognise the maritime line drawn by UN forces and blamed South Korean military exercises near Yeonpyeong Island this week for the clash, calling them a violation of its territory.

Four South Koreans – two marines and two civilians – were killed in the hour-long skirmish on Tuesday after North Korea unleashed a hail of artillery on the Yeonpyeong. The island was quiet this morning, with most residents having evacuated to the mainland.

Marines with M-16 rifles patrolled a seawall, while others gazed toward North Korea from a guard post on a cliff. Technicians worked to restore communication lines. The heightened animosity between the Koreas is taking place as the North undergoes a delicate transition of power from leader Kim Jong Il to his son Kim Jong Un, who is in his late 20s and is expected to eventually succeed his ailing father.

The South Korean president, Lee Myung-bak, has ordered reinforcements for about 4,000 troops on Yeonpyeong and four other Yellow Sea islands, as well as top-level weaponry for the soldiers and upgraded rules of engagement that would create a new category of response when civilian areas are targeted.

North Korea blamed South Korean drills this week as the motivation behind its attack but Lee said the South could not afford to abandon such preparation now.

"We should not ease our sense of crisis in preparation for the possibility of another provocation by North Korea," spokesman Hong Sang-pyo quoted Lee as saying. "A provocation like this can recur any time."

Washington and Seoul also ratcheted up pressure on China, North Korea's main ally and biggest benefactor, to restrain Pyongyang.

Without criticising the North, the Chinese premier, Wen Jiabao, responded by calling on all sides to show "maximum restraint" and pushed again to restart the six-nation talks aimed at persuading North Korea to dismantle its nuclear programmes in exchange for aid. China's foreign minister, Yang Jiechi, meanwhile, cancelled a trip to Seoul this week.

On Thursday, Lee accepted the resignation of his defence minister, Kim Tae-young, after lawmakers criticised the government, claiming officials were unprepared for the attack and that the military response was too slow.